Abdur Rahman bin Mahdi عبد الرحمن بن مهدي · The Book of Wills

"I asked Ibn Abi Awfa: 'Did the Messenger of Allah leave a will?' He said: 'No.' I said: 'How come it is prescribed for the Muslims to make wills?' He said: 'He left instructions urging the Muslims to adhere to the Book of Allah.'"